The present invention refers to a dual drum drive unit, in particular for a ropeway, of the type having at least one motor.
Such drive units are frequently used for ropeways in which a carriage is held via a rope and a counter rope by a track carrying rope, with the carriage being clamped upon the track carrying rope by means of a locking device which is controlled by both ropes. Subsequently one of the ropes is reeled off and used as load-carrying rope for receiving a load.
Known drive units of this type include for each drum a separate drive, usually two hydraulic motors. In order to tighten the counter rope, the separated arrangement of two hydraulic motors requires a provision of a respective counterpressure which, during unwinding of the respective rope, is lost as braking power. A further drawback of such a conventional drive unit is the speed-dependency of the efficiency of the hydraulic motors which means that at higher speed the efficiency considerably decreases. Moreover, the hydraulic motors which are generally used for this application are essentially provided to generate a high tensile force so that only relatively small speeds can be attained. This, however, leads to relatively time consuming idle runs in ropeways of greater length of for example 600 m or more, as used for example in logging.
Such conventional drive units encounter further problems with regard to the highly stressed hoses and seals of the hydraulic unit which may cause a shutdown of the operation. In particular, when used in less accessible regions, such operational breakdowns lead to long stoppages until the required replacement parts are delivered on site.